Water and wastewater rates are expected to rise in the coming years, and there's not much the City Council can do about it if they want to maintain optimal water quality and stave off a federal lawsuit.

The City Council voted 6-to-3 Tuesday to support an increase in water and wastewater rates that will cost average residential users a few dollars a month more while generating an additional $16 million for the city each of the next two years.

City Council members Michael Hunter, Lucy Rubio and Carolyn Vaughn voted against the increase.

In rare form, City Attorney Miles Risley interjected during the debate on water rates to remind the council that the city is still facing an "intense threat" of legal action from the federal government for its wastewater system.

"These capital improvement programs do not exist on their own," Risley said. "They are watched very closely by the federal government."

Still, for the average user, their wastewater bill likely won't change much, and lighter users will likely see reduced bills.

That's because the city is switching from a system of basing the annual rates on the lowest volume quarter and instead charging a constant rate based on usage year-round.

The wastewater system isn't the only part of the water utilities division under pressure to increase the amount of money being poured into upgrades.

The city is almost nine months removed from the most recent water quality scare, but that string of trouble-free months likely wouldn't continue should the city not raise rates, city officials told the council Tuesday.

"Well be right back where we were a year ago if we we're not moving ahead and making improvements to the system," said Dan Grimsbo, the city's interim executive director of utilities.

City Councilman Rudy Garza advocated for the rate change because the significant capital improvements needed under the council's recently adopted wastewater system overhaul will require even sharper increases in the future if no action is taken this year.

Still, the council is expected to continue exploring alternatives to rate increases as the budget discussions continue this fall.